A technique of photographing a plurality of images having different orientations using a digital camera to generate a panoramic image having a wider field of view than one image by image processing of combining the image data of the plurality of images is known. Various methods of utilizing such panoramic image are known such as expressing the views of the interior or the surrounding of an object in an easy-to-understand manner as an advertisement of a real estate and showing an exhibition of visually reproducing the space of a museum rather than showing just a bird's-eye view image as in the related art.
With the spread of high-performance terminals such as smartphones having a digital photographing function, anyone can easily photograph an image and share the image on the Internet or the like, and a general demand for generating attractive contents is very high.
“360 Panorama” (see Non-Patent Literature 1) (product of Occipital Inc.) is an example of an application that provides a function of allowing users to photograph a panoramic image using a smartphone. With this application, it is possible to reproduce an image in an arbitrary direction from a photographing point by continuously photographing a number of images adjacent in vertical and horizontal directions using a digital photographing function and pasting the images to the inner surface of an imaginary sphere by image processing in a main body.
Such a simple panoramic image generation function is sufficient for enjoying as a hobby but has a problem in that the image quality is low for using as commercial advertisements or exhibitions in a museum. Thus, equipment in which a digital single-lens reflex camera having a wide-angle lens attached thereto and a special head are combined is generally used for such a purpose of photographing. For example, “Nodal Ninja 4” (see Non-Patent Literature 2) (product of Fanotec Corporation) is a head mounted on a tripod, capable of holding a digital single-lens reflex camera at an arbitrary angle and fixing the camera so that a nodal point of the lens corresponds to the center of rotation.
The following patent literatures disclose apparatuses for photographing panoramic images.
First, Patent Literature 1 proposes a camera for photographing panoramic pictures in which a rotation jig of which the center of rotation is at a first principal point of a lens is arranged. The rotation jig is a technique of allowing users to photograph panoramic pictures easily, and a user rotates a camera body with his or her hands using the rotation jig to perform photographing sequentially. Patent Literature 1 discloses that a rotation angle is determined using a rotation angle meter or an orientation is determined using a stopper or the like that prevents a rotation of a camera from a set rotation angle.
The technique disclosed in Patent Literature 2 proposes that a nodal point of a principal lens is set to the position of a tripod attachment screw hole formed in a camera itself. Thus, a special jig for aligning the nodal point to the center of rotation is not required, and an accurate panoramic picture material with no parallax can be photographed using a panoramic photography head and a tripod.